Using the parametrized entangled state representations we have found a generalized Hankel transformationwith the integral kernel being a combination of Bessel functions.This generalized Hankel transformation correspon...Using the parametrized entangled state representations we have found a generalized Hankel transformationwith the integral kernel being a combination of Bessel functions.This generalized Hankel transformation corresponds tothe appropriate quantum mechanical representation transformation.展开更多
In this paper,the model reduction method based on κ-nearest-neighbors is provided for the parametrized nonlocal partial differential equations(PDEs).In comparison to standard local PDEs,the stiffness matrix of the co...In this paper,the model reduction method based on κ-nearest-neighbors is provided for the parametrized nonlocal partial differential equations(PDEs).In comparison to standard local PDEs,the stiffness matrix of the corresponding nonlocal model loses sparsity due to the nonlocal interaction parameter δ.Specially the nonlocal model contains uncertain parameters,enhancing the complexity of computation.In order to improve the computation efficiency,we combine the κ-nearest-neighbors with the model reduction method to construct the efficient surrogate models of the parametrized nonlocal problems.This method is an offline-online mechanism.In the offline phase,we develop the full-order model by using the quadratic finite element method(FEM)to generate snapshots and employ the model reduction method to process the snapshots and extract their key characters.In the online phase,we utilize κ-nearest-neighbors regression to construct the surrogate model.In the numerical experiments,we first verify the convergence rate when applying quadratic FEM to the nonlocal problems.Subsequently,for the linear and nonlinear nonlocal problems with random inputs,the numerical results illustrate the efficiency and accuracy of the surrogate models.展开更多
In this work we consider the Reduced Basis method for the solution of parametrized advection-reaction partial differential equations. For the generation of the basis we adopt a stabilized finite element method and we ...In this work we consider the Reduced Basis method for the solution of parametrized advection-reaction partial differential equations. For the generation of the basis we adopt a stabilized finite element method and we define the Reduced Basis method in the ＂primal- dual＂ formulation for this stabilized problem. We provide a priori Reduced Basis error estimates and we discuss the effects of the finite element approximation on the Reduced Basis error. We propose an adaptive algorithm, based on the a posteriori Reduced Basis error estimate, for the selection of the sample sets upon which the basis are built; the idea leading this algorithm is the minimization of the computational costs associated with the solution of the Reduced Basis problem. Numerical tests demonstrate the efficiency, in terms of computational costs, of the ＂primal-dual＂ Reduced Basis approach with respect to an ＂only primal＂ one. Parametrized advection-reaction partial differential equations, Reduced Basis method, ＂primal-dual＂ reduced basis approach, Stabilized finite element method, a posteriori error estimation.展开更多
In this paper we consider(hierarchical,Lagrange)reduced basis approximation and a posteriori error estimation for potential flows in affinely parametrized geometries.We review the essential ingredients:i)a Galerkin pr...In this paper we consider(hierarchical,Lagrange)reduced basis approximation and a posteriori error estimation for potential flows in affinely parametrized geometries.We review the essential ingredients:i)a Galerkin projection onto a lowdimensional space associated with a smooth“parametric manifold”in order to get a dimension reduction;ii)an efficient and effective greedy sampling method for identification of optimal and numerically stable approximations to have a rapid convergence;iii)an a posteriori error estimation procedure:rigorous and sharp bounds for the linearfunctional outputs of interest and over the potential solution or related quantities of interest like velocity and/or pressure;iv)an Offline-Online computational decomposition strategies to achieve a minimum marginal computational cost for high performance in the real-time and many-query(e.g.,design and optimization)contexts.We present three illustrative results for inviscid potential flows in parametrized geometries representing a Venturi channel,a circular bend and an added mass problem.展开更多
Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical si...Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.展开更多
Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive exa...Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive examination of curtain walls from an energy-engineering perspective,highlighting their structural typologies(Stick and Unitized),material configurations,and integration with smart technologies such as electrochromic glazing,parametric design algorithms,and Building Management Systems(BMS).Thestudy explores the thermal,acoustic,and solar performance of curtain walls across various climatic zones,supported by comparative analyses and iconic case studies including Apple Park,Burj Khalifa,and Milad Tower.Key challenges—including installation complexity,high maintenance costs,and climate sensitivity—are critically assessed alongside proposed solutions.A central innovation of this work lies in framing curtain walls not only as passive architectural elements but as dynamic interfaces that modulate energy flows,reduce HVAC loads,and enhance occupant comfort.The reviewed data indicate that optimized curtain wall configurations—especially those integrating electrochromic glazing and BIPV modules—can achieve annual energy consumption reductions ranging fromapproximately 5%to 27%,depending on climate,control strategy,and facade typology.The findings offer a valuable reference for architects,energy engineers,and decision-makers seeking to integrate high-performance facades into future-ready building designs.展开更多
A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pr...A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.展开更多
In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on...In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on head modelling and proposes a generic head parametric model based on neural radiance fields.Specifically,we first use face recognition networks and 3D facial expression database FaceWarehouse to parameterize identity and expression semantics,respectively,and use both as conditional inputs to build a neural radiance field for the human head,thereby improving the head model’s representation ability while ensuring editing capabilities for the identity and expression of the rendered results;then,through a combination of volume rendering and neural rendering,the 3D representation of the head is rapidly rendered into the 2D plane,producing a high-fidelity image of the human head.Thanks to the well-designed loss functions and good implicit representation of the neural radiance field,our model can not only edit the identity and expression independently,but also freely modify the virtual camera position of the rendering results.It has excellent multi-view consistency,and has many applications in novel view synthesis,pose driving and more.展开更多
An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as t...An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as the amplitude of the liquid column oscillations increases,parametric oscillations of the interface are excited in the form of a standing wave located in the channel plane.In particular,depending on the interfacial tension,the standing waves have a frequency equal to that of liquid piston oscillations(harmonic response),or half of the frequency of oscillations of the liquid column in the channel(subharmonic response).The detected type of instability has a gravitational-capillary nature and is analogous to Faraday waves.The analysis of the overcritical dynamics of wave oscillations indicates that interfacial tension plays a crucial role in determining the type of parametric instability.At high interfacial tension,only synchronous(harmonic)wave modes are observed,and the threshold of the wave excitation is determined by the amplitude of piston oscillations of the liquid column.In this case,the oscillation acceleration does not play a role and has a small value in the threshold of the synchronous mode response.In the case of weak surface tension,subharmonic oscillations are observed.The threshold for the development of these oscillations is determined by the dimensionless acceleration of the oscillating liquid column and remains almost constant with variations in the dimensionless frequency of oscillations.At moderate values of interfacial tension(in the region of moderate dimensionless frequencies),a synchronous wave mode emerges in the stability threshold of the oscillating interface.As the dimensionless acceleration is increased further,a subharmonic mode is excited.The growth of subharmonic oscillations occurs against the background of harmonic wave oscillations,with the oscillations of the interface representing a combination of two standing waves.展开更多
Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to exa...Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to examine the 6-DOF motion characteristics of a conceptual semi-submersible platform equipped with a hollow moonpool(SPHM).The experimental results indicate that heave motions of the SPHM demonstrate suboptimal performance,potentially due to the natural heave period coinciding with the predominant wave energy range in the South China Sea.Furthermore,parametric rolling was observed during both regular and irregular wave tests and analyzed through Mathieu's equation.The analysis reveals that parametric rolling of the SPHM exhibits primarily low-frequency motion with substantial amplitudes,with its period matching the natural roll period.Notably,parametric rolling persists for only several natural roll periods of the platform,leading to considerable variance in roll motions.展开更多
Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,...Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,owing to their flexible and resilient traits.By means of a straightforward and cost-effective method to achieve structure-driven,vibration-driven tensegrity shows great potential,particularly in tasks demanding random exploration.However,the design guidance for vibration-driven tensegrity and their performance evaluation in unstructured terrain remain unrevealed due to the complex dynamics of the structure.This paper presents a small six-bar tensegrity robot,driven by wireless vibration motors,designed for deployment in disaster rescue and search scenarios.Finite element simulation is used to investigate how structural characteristics,excitation parameters,and the arrangement of motors affect the kinematic performance of this tensegrity system.A prototype of the six-bar tensegrity robot with three motors located on the lower ends of the three lower struts is designed and manufactured after the numerical simulations.A simple control policy which adjusts the motion of the tensegrity robot by turning on or off the motors on different locations is proposed.The prototype with and without the control policy is tested in man-made environments of various complexity.It shows that the ability and efficiency of the tensegrity robot in exploring unstructured environments is significantly enhanced by the proposed control policy.It is believed that the potential of the vibration-driven tensegrity robot could be further exploited by integrating multi-source sensors and more intelligent control policies.展开更多
Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-...Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-tailed distribution.Adding one more parameter to the power XLindley distribution improves this new distribution,especially when modeling leptokurtic lifetime data.The suggested density provides greater flexibility with asymmetric forms and different degrees of peakedness.Its statistical features,like the quantile function,moments,extropy measures,incomplete moments,stochastic ordering,and stress-strength parameters,are explored.We further investigate its use in actuarial science through the computation of pertinent metrics,such as value-at-risk,tail value-at-risk,tail variance,and tail variance premium.To obtain the point and interval parameter estimates,we use the maximum likelihood estimation approach.We do many simulation tests to evaluate the performance of our proposed estimator.Metrics like bias,relative bias,mean squared error,root mean squared error,average interval length,and coverage probability will be used in these tests to assess the estimator’s performance.To illustrate the practical value of our proposed model,we apply it to analyze three real-world datasets.We then compare its performance to established competing models,highlighting its advantages.展开更多
Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic ...Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic cell to design a family of inflatable origami tubular structures with the targeted configuration.First,the classification of rigid foldable degree-4 vertices is studied thoroughly.Since the proposed GMTC is comprised of forming units(FU)and linking units(LU),types of FUs and LUs are investigated based on the classification of degree-4 vertices,respectively.The rigid foldability of the GMTC is presented by studying the kinematics of the FUs and LUs.Volume of the GMTC is analyzed to investigate multistable configurations of the basic cell.The variations in volume of the GMTC offer great potential for developing the inflatable tubular structure.Design method and parametric optimization of the tubular structure with targeted configuration are proposed.The feasibility of the approach is validated by the approximation of four different cases,namely parabolic,semicircular,trapezoidal,and straight-arc hybrid tubular structures.展开更多
We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish...We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish the boundedness of higher-order commutators ofμ_(S)^(?)andμ_(λ),^(*,?)with BMO functions applying some properties of variable exponents and generalized BMO norms.展开更多
We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, ext...We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.展开更多
To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive e...To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive evaluation of energy,exergy and economic performance of the ORC system was conducted deeply.The energy,exergy and economic performance models of the ORC system were established,and proper candidate organic working fluids(OWFs)were selected based on the thermo-physical properties of OWF and operating characteristics of ORC system.Then,the effects of ORC crucial parameters on the system energy,exergy and economic performances were evaluated in detail.Finally,the bi-objective optimization based on the genetic algorithm was conducted to analyze the optimal performance of the ORC system under the designed ORC crucial parameters,and the exergy efficiency and electricity production cost were set as the evaluation indexes of parametric optimization.The results indicate that the ORC system with the higher evaporation temperature and lower condensation temperature can obtain the larger system exergy efficiency and smaller electricity production cost.The smaller the superheat degree of OWF and pinch-point temperature difference in the evaporator are,the better the energy and exergy performances of the ORC system are.Under the optimization results,R245fa has the best comprehensive performance with the exergy efficiency of 46.34%and electricity production cost of 0.12123$/kWh among the selected candidate OWFs,which should be preferentially chosen as the OWF of the ORC system.展开更多
To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground moti...To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.展开更多
Photon pairs with large nondegeneracy have recently attracted increasing interest, which gives rise to an urgent demand for revealing their complete and accurate spectral distribution. By thoroughly analyzing parametr...Photon pairs with large nondegeneracy have recently attracted increasing interest, which gives rise to an urgent demand for revealing their complete and accurate spectral distribution. By thoroughly analyzing parametric down-conversion(PDC), we put forward a model to directly describe the spatial-spectral distribution of these photon pairs, which is experimentally demonstrated by a 532-nm pumped type-I PDC in a beta barium borate(BBO) crystal. The measured spectral curves show good agreement with the theoretical predictions over the entire spectral range. We further demonstrate that, as signal wavelength increases, the photon pairs are initially spectrally distinguishable, then partly indistinguishable, finally completely indistinguishable with a maximum bandwidth of approximately 500 nm. Utilizing photon-number-resolving single-photon detectors(SPD), we observe the average photon number decreases significantly more slowly than the spectral intensity as the wavelength deviates from the peak, and the photon numbers follow a quasi-Poisson distribution well for wavelengths around the peak, but a thermal distribution better describes the statistics near the spectral boundaries. Finally,we use the signal photons as the trigger to generate heralded Fock states up to 10 photons in near-infrared range, which are suitable for quantum simulation and quantum key distribution in optical fiber networks.展开更多
We present a systematic experimental investigation of temporal contrast enhancement techniques for petawatt(PW)-class Ti:sapphire lasers utilizing a double chirped-pulse amplification(CPA)architecture.Particular atten...We present a systematic experimental investigation of temporal contrast enhancement techniques for petawatt(PW)-class Ti:sapphire lasers utilizing a double chirped-pulse amplification(CPA)architecture.Particular attention is given to pre-pulses induced by post-pulses originating in the first CPA stage.One conventional and two advanced pulse-cleaning strategies are quantitatively evaluated:(i)a saturable absorber(SA),(ii)a femtosecond optical parametric amplifier(OPA)employing the idler pulse in a two-stage configuration,and(iii)sum-frequency generation(SFG)combining the signal and idler pulses from the OPA.All techniques are implemented and evaluated using the J-KAREN-P laser system with an output energy of about 20 J.To the best of our knowledge,this is the first report to directly and systematically compare the contrast of pre-pulses originating from the first CPA stage under identical experimental conditions in a high-energy PW-class laser facility.The results offer crucial insights into contrast optimization for future high-field applications.展开更多
基金National Natural Science Foundation of China under Grant Nos.10475056 and 10775097
文摘Using the parametrized entangled state representations we have found a generalized Hankel transformationwith the integral kernel being a combination of Bessel functions.This generalized Hankel transformation corresponds tothe appropriate quantum mechanical representation transformation.
基金supported by National Key R&D Program of China(No.2021YFA1001300)Natural Science Foundation of Hunan Province(Nos.2021JJ30084,2022JJ40030)+3 种基金National Natural Science Foundation of China(Nos.12271150,12101216)Hong Kong Research Grants Council grant 15303121the Hong Kong Polytechnic University Postdoctoral Research Fund 1-W261Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012548).
文摘In this paper,the model reduction method based on κ-nearest-neighbors is provided for the parametrized nonlocal partial differential equations(PDEs).In comparison to standard local PDEs,the stiffness matrix of the corresponding nonlocal model loses sparsity due to the nonlocal interaction parameter δ.Specially the nonlocal model contains uncertain parameters,enhancing the complexity of computation.In order to improve the computation efficiency,we combine the κ-nearest-neighbors with the model reduction method to construct the efficient surrogate models of the parametrized nonlocal problems.This method is an offline-online mechanism.In the offline phase,we develop the full-order model by using the quadratic finite element method(FEM)to generate snapshots and employ the model reduction method to process the snapshots and extract their key characters.In the online phase,we utilize κ-nearest-neighbors regression to construct the surrogate model.In the numerical experiments,we first verify the convergence rate when applying quadratic FEM to the nonlocal problems.Subsequently,for the linear and nonlinear nonlocal problems with random inputs,the numerical results illustrate the efficiency and accuracy of the surrogate models.
基金support provided thorough the "Progetto Rocca", MIT-Politecnico di Milano collaboration
文摘In this work we consider the Reduced Basis method for the solution of parametrized advection-reaction partial differential equations. For the generation of the basis we adopt a stabilized finite element method and we define the Reduced Basis method in the ＂primal- dual＂ formulation for this stabilized problem. We provide a priori Reduced Basis error estimates and we discuss the effects of the finite element approximation on the Reduced Basis error. We propose an adaptive algorithm, based on the a posteriori Reduced Basis error estimate, for the selection of the sample sets upon which the basis are built; the idea leading this algorithm is the minimization of the computational costs associated with the solution of the Reduced Basis problem. Numerical tests demonstrate the efficiency, in terms of computational costs, of the ＂primal-dual＂ Reduced Basis approach with respect to an ＂only primal＂ one. Parametrized advection-reaction partial differential equations, Reduced Basis method, ＂primal-dual＂ reduced basis approach, Stabilized finite element method, a posteriori error estimation.
文摘In this paper we consider(hierarchical,Lagrange)reduced basis approximation and a posteriori error estimation for potential flows in affinely parametrized geometries.We review the essential ingredients:i)a Galerkin projection onto a lowdimensional space associated with a smooth“parametric manifold”in order to get a dimension reduction;ii)an efficient and effective greedy sampling method for identification of optimal and numerically stable approximations to have a rapid convergence;iii)an a posteriori error estimation procedure:rigorous and sharp bounds for the linearfunctional outputs of interest and over the potential solution or related quantities of interest like velocity and/or pressure;iv)an Offline-Online computational decomposition strategies to achieve a minimum marginal computational cost for high performance in the real-time and many-query(e.g.,design and optimization)contexts.We present three illustrative results for inviscid potential flows in parametrized geometries representing a Venturi channel,a circular bend and an added mass problem.
基金financially supported by the National Key Research and Development Program of China (2022YFB3706802)。
文摘Automation and intelligence have become the primary trends in the design of investment casting processes.However,the design of gating and riser systems still lacks precise quantitative evaluation criteria.Numerical simulation plays a significant role in quantitatively evaluating current processes and making targeted improvements,but its limitations lie in the inability to dynamically reflect the formation outcomes of castings under varying process conditions,making real-time adjustments to gating and riser designs challenging.In this study,an automated design model for gating and riser systems based on integrated parametric 3D modeling-simulation framework is proposed,which enhances the flexibility and usability of evaluating the casting process by simulation.Firstly,geometric feature extraction technology is employed to obtain the geometric information of the target casting.Based on this information,an automated design framework for gating and riser systems is established,incorporating multiple structural parameters for real-time process control.Subsequently,the simulation results for various structural parameters are analyzed,and the influence of these parameters on casting formation is thoroughly investigated.Finally,the optimal design scheme is generated and validated through experimental verification.Simulation analysis and experimental results show that using a larger gate neck(24 mm in side length) and external risers promotes a more uniform temperature distribution and a more stable flow state,effectively eliminating shrinkage cavities and enhancing process yield by 15%.
文摘Curtain wall systems have evolved from aesthetic facade elements into multifunctional building envelopes that actively contribute to energy efficiency and climate responsiveness.This reviewpresents a comprehensive examination of curtain walls from an energy-engineering perspective,highlighting their structural typologies(Stick and Unitized),material configurations,and integration with smart technologies such as electrochromic glazing,parametric design algorithms,and Building Management Systems(BMS).Thestudy explores the thermal,acoustic,and solar performance of curtain walls across various climatic zones,supported by comparative analyses and iconic case studies including Apple Park,Burj Khalifa,and Milad Tower.Key challenges—including installation complexity,high maintenance costs,and climate sensitivity—are critically assessed alongside proposed solutions.A central innovation of this work lies in framing curtain walls not only as passive architectural elements but as dynamic interfaces that modulate energy flows,reduce HVAC loads,and enhance occupant comfort.The reviewed data indicate that optimized curtain wall configurations—especially those integrating electrochromic glazing and BIPV modules—can achieve annual energy consumption reductions ranging fromapproximately 5%to 27%,depending on climate,control strategy,and facade typology.The findings offer a valuable reference for architects,energy engineers,and decision-makers seeking to integrate high-performance facades into future-ready building designs.
基金supported by the National Natural Science Foundation of China(No.52175067)the Zhejiang Key Research&Development Project(No.2021C01021)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY20E050016)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(No.GZC20241478)。
文摘A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.
文摘In recent years,the concept of digital human has attracted widespread attention from all walks of life,and the modelling of high-fidelity human bodies,heads,and hands has been intensively studied.This paper focuses on head modelling and proposes a generic head parametric model based on neural radiance fields.Specifically,we first use face recognition networks and 3D facial expression database FaceWarehouse to parameterize identity and expression semantics,respectively,and use both as conditional inputs to build a neural radiance field for the human head,thereby improving the head model’s representation ability while ensuring editing capabilities for the identity and expression of the rendered results;then,through a combination of volume rendering and neural rendering,the 3D representation of the head is rapidly rendered into the 2D plane,producing a high-fidelity image of the human head.Thanks to the well-designed loss functions and good implicit representation of the neural radiance field,our model can not only edit the identity and expression independently,but also freely modify the virtual camera position of the rendering results.It has excellent multi-view consistency,and has many applications in novel view synthesis,pose driving and more.
基金supported by the Ministry of Education of the Russian Federation(Project No.1023032300071-6-2.3.1).
文摘An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted.It has been found that as the amplitude of the liquid column oscillations increases,parametric oscillations of the interface are excited in the form of a standing wave located in the channel plane.In particular,depending on the interfacial tension,the standing waves have a frequency equal to that of liquid piston oscillations(harmonic response),or half of the frequency of oscillations of the liquid column in the channel(subharmonic response).The detected type of instability has a gravitational-capillary nature and is analogous to Faraday waves.The analysis of the overcritical dynamics of wave oscillations indicates that interfacial tension plays a crucial role in determining the type of parametric instability.At high interfacial tension,only synchronous(harmonic)wave modes are observed,and the threshold of the wave excitation is determined by the amplitude of piston oscillations of the liquid column.In this case,the oscillation acceleration does not play a role and has a small value in the threshold of the synchronous mode response.In the case of weak surface tension,subharmonic oscillations are observed.The threshold for the development of these oscillations is determined by the dimensionless acceleration of the oscillating liquid column and remains almost constant with variations in the dimensionless frequency of oscillations.At moderate values of interfacial tension(in the region of moderate dimensionless frequencies),a synchronous wave mode emerges in the stability threshold of the oscillating interface.As the dimensionless acceleration is increased further,a subharmonic mode is excited.The growth of subharmonic oscillations occurs against the background of harmonic wave oscillations,with the oscillations of the interface representing a combination of two standing waves.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFC2806300)。
文摘Semi-submersible platforms operating in deep seas encounter complex environmental conditions,making experimental studies on their global performance essential for new platform designs.Model tests were conducted to examine the 6-DOF motion characteristics of a conceptual semi-submersible platform equipped with a hollow moonpool(SPHM).The experimental results indicate that heave motions of the SPHM demonstrate suboptimal performance,potentially due to the natural heave period coinciding with the predominant wave energy range in the South China Sea.Furthermore,parametric rolling was observed during both regular and irregular wave tests and analyzed through Mathieu's equation.The analysis reveals that parametric rolling of the SPHM exhibits primarily low-frequency motion with substantial amplitudes,with its period matching the natural roll period.Notably,parametric rolling persists for only several natural roll periods of the platform,leading to considerable variance in roll motions.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178175 and 52108182)the National Natural Science Foundation of Zhejiang Province(Grant No.LZ23E080003).
文摘Tensegrity structures,embodying the principles of continuous tensioning and discrete compression,have emerged as fundamental frameworks in locomotive soft robotics for navigating uneven and unpredictable environments,owing to their flexible and resilient traits.By means of a straightforward and cost-effective method to achieve structure-driven,vibration-driven tensegrity shows great potential,particularly in tasks demanding random exploration.However,the design guidance for vibration-driven tensegrity and their performance evaluation in unstructured terrain remain unrevealed due to the complex dynamics of the structure.This paper presents a small six-bar tensegrity robot,driven by wireless vibration motors,designed for deployment in disaster rescue and search scenarios.Finite element simulation is used to investigate how structural characteristics,excitation parameters,and the arrangement of motors affect the kinematic performance of this tensegrity system.A prototype of the six-bar tensegrity robot with three motors located on the lower ends of the three lower struts is designed and manufactured after the numerical simulations.A simple control policy which adjusts the motion of the tensegrity robot by turning on or off the motors on different locations is proposed.The prototype with and without the control policy is tested in man-made environments of various complexity.It shows that the ability and efficiency of the tensegrity robot in exploring unstructured environments is significantly enhanced by the proposed control policy.It is believed that the potential of the vibration-driven tensegrity robot could be further exploited by integrating multi-source sensors and more intelligent control policies.
基金supported by researchers Supporting Project Number(RSPD2025R548)King Saud University,Riyadh,Saudi Arabia.
文摘Accurately modeling heavy-tailed data is critical across applied sciences,particularly in finance,medicine,and actuarial analysis.This work presents the heavy-tailed power XLindley distribution(HTPXLD),a unique heavy-tailed distribution.Adding one more parameter to the power XLindley distribution improves this new distribution,especially when modeling leptokurtic lifetime data.The suggested density provides greater flexibility with asymmetric forms and different degrees of peakedness.Its statistical features,like the quantile function,moments,extropy measures,incomplete moments,stochastic ordering,and stress-strength parameters,are explored.We further investigate its use in actuarial science through the computation of pertinent metrics,such as value-at-risk,tail value-at-risk,tail variance,and tail variance premium.To obtain the point and interval parameter estimates,we use the maximum likelihood estimation approach.We do many simulation tests to evaluate the performance of our proposed estimator.Metrics like bias,relative bias,mean squared error,root mean squared error,average interval length,and coverage probability will be used in these tests to assess the estimator’s performance.To illustrate the practical value of our proposed model,we apply it to analyze three real-world datasets.We then compare its performance to established competing models,highlighting its advantages.
基金supported by the National Natural Science Foundation of China(No.52222501,52075016,52192632)the Fundamental Research Funds for the Central Universities(Grant No.YWF-23-L-904).
文摘Inflatable deployable structures inspired by origami have significant applications in space missions such as solar arrays and antennas.In this paper,a generalized Miura-ori tubular cell(GMTC)is presented as the basic cell to design a family of inflatable origami tubular structures with the targeted configuration.First,the classification of rigid foldable degree-4 vertices is studied thoroughly.Since the proposed GMTC is comprised of forming units(FU)and linking units(LU),types of FUs and LUs are investigated based on the classification of degree-4 vertices,respectively.The rigid foldability of the GMTC is presented by studying the kinematics of the FUs and LUs.Volume of the GMTC is analyzed to investigate multistable configurations of the basic cell.The variations in volume of the GMTC offer great potential for developing the inflatable tubular structure.Design method and parametric optimization of the tubular structure with targeted configuration are proposed.The feasibility of the approach is validated by the approximation of four different cases,namely parabolic,semicircular,trapezoidal,and straight-arc hybrid tubular structures.
基金Supported by the Natural Science Research Project of Anhui Educational Committee(Grant No.2024AH050129)。
文摘We prove the boundedness of the parametric Lusin's S functionμ_(S)^(?)(f)and Littlewood-Paley's g_(λ)^(*)-funtionμ_(λ),^(*,?)(f)on grand Herz-Morrey spaces with variable exponents.Additionally,we establish the boundedness of higher-order commutators ofμ_(S)^(?)andμ_(λ),^(*,?)with BMO functions applying some properties of variable exponents and generalized BMO norms.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 52471200, 12174165, and 52201219)。
文摘We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.
基金the financial support for this work provided by the National Natural Science Foundation of China(51974087)Anhui Provincial Natural Science Foundation(1908085QE203)+1 种基金University Natural Science Research Foundation of Anhui Province(2022AH050262)Science Research Foundation of Anhui Jianzhu University(2020QDZ02).
文摘To further enhance the recovery rate of low-temperature waste heat,the low-temperature flue gas in the sinter annular cooler was chosen as the heat source of an organic Rankine cycle(ORC)system,and the comprehensive evaluation of energy,exergy and economic performance of the ORC system was conducted deeply.The energy,exergy and economic performance models of the ORC system were established,and proper candidate organic working fluids(OWFs)were selected based on the thermo-physical properties of OWF and operating characteristics of ORC system.Then,the effects of ORC crucial parameters on the system energy,exergy and economic performances were evaluated in detail.Finally,the bi-objective optimization based on the genetic algorithm was conducted to analyze the optimal performance of the ORC system under the designed ORC crucial parameters,and the exergy efficiency and electricity production cost were set as the evaluation indexes of parametric optimization.The results indicate that the ORC system with the higher evaporation temperature and lower condensation temperature can obtain the larger system exergy efficiency and smaller electricity production cost.The smaller the superheat degree of OWF and pinch-point temperature difference in the evaporator are,the better the energy and exergy performances of the ORC system are.Under the optimization results,R245fa has the best comprehensive performance with the exergy efficiency of 46.34%and electricity production cost of 0.12123$/kWh among the selected candidate OWFs,which should be preferentially chosen as the OWF of the ORC system.
基金National Natural Science Foundation of China under Grant No.52478568National Key R&D Program of China under Grant Nos.2021YFC3100701 and 2022YFC3003503the Nature Science Foundation of Hubei Province under Grant No.2023AFA030。
文摘To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.
基金Project supported by the National Natural Science Foundation of China (Grant No. 62075010)。
文摘Photon pairs with large nondegeneracy have recently attracted increasing interest, which gives rise to an urgent demand for revealing their complete and accurate spectral distribution. By thoroughly analyzing parametric down-conversion(PDC), we put forward a model to directly describe the spatial-spectral distribution of these photon pairs, which is experimentally demonstrated by a 532-nm pumped type-I PDC in a beta barium borate(BBO) crystal. The measured spectral curves show good agreement with the theoretical predictions over the entire spectral range. We further demonstrate that, as signal wavelength increases, the photon pairs are initially spectrally distinguishable, then partly indistinguishable, finally completely indistinguishable with a maximum bandwidth of approximately 500 nm. Utilizing photon-number-resolving single-photon detectors(SPD), we observe the average photon number decreases significantly more slowly than the spectral intensity as the wavelength deviates from the peak, and the photon numbers follow a quasi-Poisson distribution well for wavelengths around the peak, but a thermal distribution better describes the statistics near the spectral boundaries. Finally,we use the signal photons as the trigger to generate heralded Fock states up to 10 photons in near-infrared range, which are suitable for quantum simulation and quantum key distribution in optical fiber networks.
基金supported by the Japan Society for the Promotion of Science(Grant Nos.JP 15F15772,JP 16H03911,JP 16K05506,JP 19H00669,and JP 25H00621)the Precursory Research for Embryonic Science and Technology(Grant No.JPMJPR16P9)+1 种基金the MEXT Project(Grant No.JPMXS0450300221)the Japan Science and Technology Agency(Grant No.PRESTOJPMJPR16P9).
文摘We present a systematic experimental investigation of temporal contrast enhancement techniques for petawatt(PW)-class Ti:sapphire lasers utilizing a double chirped-pulse amplification(CPA)architecture.Particular attention is given to pre-pulses induced by post-pulses originating in the first CPA stage.One conventional and two advanced pulse-cleaning strategies are quantitatively evaluated:(i)a saturable absorber(SA),(ii)a femtosecond optical parametric amplifier(OPA)employing the idler pulse in a two-stage configuration,and(iii)sum-frequency generation(SFG)combining the signal and idler pulses from the OPA.All techniques are implemented and evaluated using the J-KAREN-P laser system with an output energy of about 20 J.To the best of our knowledge,this is the first report to directly and systematically compare the contrast of pre-pulses originating from the first CPA stage under identical experimental conditions in a high-energy PW-class laser facility.The results offer crucial insights into contrast optimization for future high-field applications.
